An electronic appliance accommodating printed wiring boards on which various electronic components are mounted has been hitherto cooled by an exhaust fan installed in the housing, heat pipes, or other heat exchangers. Or by forcing out the heat by natural convection, the box-shaped electronic appliance has been cooled.
However, when the fan is directly mounted on the housing, the housing radiant noise increases due to fan rotation noise and wind sound. Therefore, if the electronic appliance for general household use has such fan, noise is generated, and therefore the electronic appliance having such fan is not suited as an electronic household appliance. On the other hand, in the structure incorporating the fan inside of the housing, molded parts must be newly added for exhausting the heat outside of the housing or taking in air. As a result, the manufacturing cost is higher. The electronic appliance having heat pipes or other heat exchangers, expensive heat countermeasure parts are needed. Therefore, because of high product cost, electronic appliances having such heat exchangers are not suited as electronic household appliances.